It has been found that when clothes are washed in laundry detergents containing lipase, an unattractive odor resembling the odor of spit-up from babies can remain on the fabric afterward. It is believed that lipase, which is adsorbed on fabric stains in the wash cycle, continues to function in the rinse cycle and the dryer. Without meaning to be bound by theory, it is believed that this malodor is produced by the hydrolysis, which is catalyzed by lipase, of short chain triglycerides in some soils on the fabric. The hydrolysis produces free fatty acids (e.g. butyric acid) having a malodor. If the hydrolytic products are not completely removed during the wash or rinse cycles, the odor persists on dry fabrics, especially where there are dairy product stains. Experimental evidence shows that the intensity of odor peaks after about two days of storage of the dry garment.
It has been found that including a certain amount of terpene or terpenoid in the laundry detergent can markedly reduce or eliminate this malodor. Again without meaning to be bound by theory, it is believed that this combination of lipase and terpene is effective because terpenes boil at about the same temperature (about 120.degree.-229.degree. C.) as the malodorous compounds, so both vaporize at about the same time, resulting in the elimination or reduction of the unpleasant odor.
The inclusion of lipase in laundry detergent compositions is known and is of current interest in the detergent industry. For example, U.S. Pat. No. 4,908,150, Hessel et al, issued Mar. 13, 1990 describes liquid detergent compositions containing lipolytic enzymes wherein the stability of the lipolytic enzyme is said to be improved by the inclusion of particular nonionic ethylene glycol-containing copolymers.
Terpenes and terpenoids have been disclosed as perfume components in detergent compositions. For example, U.S. Pat. No. 4,515,705, Moeddel, issued May 7, 1985 describes compositions containing proteases having no detectable odor at a concentration of less than about 0.002 Anson units per gram of distilled water, and selected perfume materials which include some terpenes. The proteases therein are odor purified. The benefit of the perfumes therein is the reduction or elimination of the unpleasant odor contribution of protease stock.
Japanese Publication HEI2-178397, Watanabe et al., laid open Jul. 11, 1990, discloses detergent compositions containing anionic surfactant; alkaline lipase which has an activity at pH 9 which is at least 30% of that at pH 7; and fragrance component(s) with a boiling point above 230.degree. C. which are 30% or more of the total fragrance composition: 0.05-1 weight %; and the ratio of the total sodium ion to potassium is within the range 4:1-1:4.
None of these publications teach or describe laundry detergent compositions comprising detersive surfactant, detergent-compatible lipase, and a certain amount of terpenes or terpenoids with a boiling point between about 120.degree. C. and about 229.degree. C.